Chronic obstructive pulmonary disease

From Ganfyd

Introduction

Progressive disorder of airways characterized by airflow obstruction, affecting about 16% of 40-70 year olds. It is responsible for about 5% of deaths. It has an accepted (GOLD standard) definition^[1]!

Aetiology

• Smoking (the modern cause par excellence)
• Exposure to particulates (classically was caused by exposure to smoke from open fires in enclosed spaces)
• Genetic (α1 anti-trypsin deficiency)
• Race: (Chinese and Afro-caribbeans have reduced susceptibility)
• Poor diet and low birthweight

Clinical features

Cough with or without sputum, wheeze and recurrant respiratory infections or difficulty in breathing on exertion.

Signs

Tachypnoea, prolonged expiration, use of accessory respiratory muscles, overinflated chest

Pink puffers are always breathless but not cyanosed.

Blue bloaters are deeply cyanosed with poor respiratory effort and oedema

Investigation

• Spirometry
• CXR
• Reversibility testing

Management

It can be regarded as a progressive chronic inflammatory process. There are catches in its management as the literature is undergoing a very vigorous debate on various inhaled therapy strategies. Exacerbations have recently been demonstrated to be associated with progression but the patient with infrequent exacerbations progreeses at a very similar rate to one with frequent exacerbations. The role of say macrolide antibiotics is unclear.

Drug therapy

• Inhaled β agonists There is evidence that if minimising side effects is the goal, best not combined with steroid^[2] but other evidence shows that compination therapy results in best net patient outcome^[3].
• Inhaled anti-cholinergic may actually be the best monotherapy^[3].
• Inhaled steroids - relieve symptoms but do not benefit survival level 1b^[4]. There may be an increase in pneumonia in stable patients if used^[5] but this might not apply to all steroid preparations^[6]. They are likely to be ineffective or harmful when added to long acting inhaled beta agonists^[7].
• Oral steroid courses appear effective in acute exacerbations with an undefined optimal dose^[8]. There is no good evidence that courses need to last more than 7 days^[9].
• Theophylline - Little evidence of real outcome change, but often used in rescue
  • Roflumilast a more selective PDE4 inhibitor seems promising
• Antibiotics Mixed evidence base
• Mucolytics

Non-drug therapy

Pulmonary rehabilitation does work.

• Smoking cessation
• Exercise
• Dietary change

Long term oxygen therapy

PRODIGY have an extensive section on long term oxygen therapy (LTOT). This can be viewed directly by clicking here.

Scoring severity of COPD

Spirometry is informative. The GOLD spirometric classification predicts hospitalisation^[10] but like all criteria has predictive problems^[11]. These are not simple to apply for those who wish to stratify the population as risk factors are not linear. A proposed scoring system suitable for general practice use is DOSE, scored on the MRC dyspnoea score; obstruction as a percentage of predicted FEV1; binary current smoking status; and the count of exacerbations in the previous or preceding year. Scores above 4 predict greater likelihood of admission and other emergency encounters. They don't predict effective ways to change that.

Prognosis

Ex smokers 40 to 80 years old with FEV₁ <60% predicted, less than 10% improvement with β-2 agonist and FEV₁/FVC <0.71^[12]

Weather and anticipatory care

The UK meteorological service (Met Office) in 2006 offered a service^[13] predicting weather likely to be associated with worsening of COPD. Suggestions have been made that specific action by medical attendants shortly in advance of that weather can reduce hospital admissions for exacerbation of COPD.

See also weather and illness.

External Links

• Global Strategy for the Diagnosis, Management and Prevention of COPD, Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2008
• PRODIGY Guideline
• NICE - Management of chronic obstructive pulmonary disease in adults in primary and secondary care
• Clinical Evidence chapter on Chronic obstructive pulmonary disease

References